Our goal is to move towards developing a simple, rapid, hand-held optical screening device which will yield low resolution tissue functional information that complements and enhances the detailed structural information obtained from x-ray mammography. The functional information obtained from the optical screening device should allow for distinguishing between healthy and diseased tissue by providing a description of the tissue cellular state. To obtain accurate, quantitative determination of the optical parameters of various types of breast tissue, we will employ our recently-developed Frequency-Domain Photon Migration (FDPM) instrument to characterize normal and malignant tissue encountered in the human breast.